Update CHANGELOG file bringing 0.9.0 in sync with JIRA.
MESOS-460: Remove LICENSE info from NOTICE: progress towards cleaning up LICENSE file too.
Fixed os::memory() and fs::available() to return Bytes.

Review: https://reviews.apache.org/r/10813
Fixed slave to use Bytes version of memory and disk.

Review: https://reviews.apache.org/r/10814
Fixed garbage collection to allow for disk head room.

Review: https://reviews.apache.org/r/10938
Fixed process isolator to safely setup launcher's environment.

Review: https://reviews.apache.org/r/10879
Fixed the resource monitor output upon collection failure.

Review: https://reviews.apache.org/r/10967
Updated post-reviews to work with the new git repository, by using
'master' instead of 'trunk'.

Review: https://reviews.apache.org/r/10968
Added the ability to install a failure signal handler, updated the
master and slave mains to do so.

Review: https://reviews.apache.org/r/10990
Changed the signal handler to use LOG(WARNING), corrected a comment.

Review: https://reviews.apache.org/r/10990
Updated post-reviews.py to use the correct apache git mirror.

Review: https://reviews.apache.org/r/11091
Fixed the MonitorTest by setting the timestamp of the
ResourceStatistics.

Review: https://reviews.apache.org/r/10715